I was reading an article about the new Viper in Hot Rod, and they described the engines VVT system. It uses what they are calling a Cam In Cam system, which allows the lobe separation angle to be altered, while lift and duration remain the same. My question is if anyone thinks that a system like this might make it to the aftermarket for other cam in block engines. If an OE manf. is using it, I would believe that it has a lot of testing behind it. Maybe this is something Bret Bauer could look into, instead of chasing girls and drinking beer!

 

I can't chase girls my old lady wouldn't like that! At least if I do she doesn't!

The setup is made by Mechadyne. Very cool idea. I've been waiting for variable pushrod cam engines, you could do some very cool stuff with this deal but lots of dyno and simulation time to come up with the lobes you need and then programing time on the dyno.

http://www.mechadyne-int.com/vva-pro...tric-camshafts

Bret

 

Ferarri's variable valve timing beats any I've seen yet. I can't find a good article on it. The cam is 3d and the valve events change from the front of the lobe towards the back of the lobe. As the engine revs higher it pulls the camshaft more towards the front of the block. I bet the cams are expensive as hell to grind though. but boy to have that freedom, your car could pull > 20 inches of vacuum at idle and great fuel economy and drive ability around town under 3000 rpm but still have enough cam to keep feeding the engine at 8000 rpm.

 

Are you sure Ferarri still uses it? I was under the notion that they no longer used that system.

 

Technology keeps movin

 

what are they using now instead? how could you get any better than that? The only thing better would be solenoid controlled valves and I was under the notion that they werent reliable above 3k rpm.

 

it seems like an interesting concept....but does it really work or will it just fade away soon after it comes out like so many other things like these over the years.....

 

Yeah I don't know if they are still using that one or not but it is a great idea. So simple in concept, yet just about perfect in function.

I thought about trying to create a simplified version for an SBC and get someone to just grind a little bit of lobe lift variation then move the came back and forth between 2 settings. Besides the obvious complications I decided that I didn't really know how the lifters would handle something like that without having the roller at an angle. But all that is beside the point, i'm too broke to try any fun projects

 

I like Mechadyne's technology for a V8 more than anything else I've seen for that solution. The Ferarri's is ok if you like flat tappets, can't do that deal with a roller, and with a pushrod motor the duration you would want to run with this system would be lower rather than higher so rollers are better.

Bret

 

I don't know what they were using now, but I was thinking they stopped using it because they were having relabilty problems, or something like that.

I won't doubt that it is a great idea, I would just be a little concerned about lobe and journal wear on the camshaft.

 

It does sound like old technology if the cam itself is adjusting the lift. BMW's have been variable valve timing (VANOS) for the past 8 years and variable valve lift (Valvetronic) for the past 5(?). The valve timing is controlled by 2 units (one for each intake and exhaust cam) which rotates them to advance or retard the camshaft timing. The variable valve lift itself is varied by eccentric shaft which acts basically like a variable rocker arm. Sweet technology.

 

pardon my foggy knowlege, but isnt the freaking VTEC cam one that changes spec as the RPM rises?

I like the idea of variable cams, we all know it gives Bret a chubby. LOL

 

VTEC just advances or retards the cam.

 

Is the VVT on the L92 also just cam advancing/retarding?

 

I always wondered if VVT could be accomplished on a single cam pushrod Chevy engine by using a loose timing chain and moving the slack from side to side with a double coupled idler roll setup controlled by a stepper motor or vacuum signal or whatever. The slack on either side would be longer or shorter depending on position causing the cam events to be later or earlier, respectively. Kind of a backyard idea, but it's been in my head for a while.